CALIBER/browser
CORPUS EXPORT · 12269 calibers · 59387 family views · round round/2026-09-08Compiled from app/public/data/ · corpus 70c0140eba.

Manufacturer

Seiko Instruments Inc. (SII)

4 designsJP1937–presentproduceragent:sii
also known asDaini Seikosha Co.HattoriSIITMITime Module Inc.

Attribution is time-dependent in this model: a design keeps its identity when a company is absorbed, and only the maker record moves. Every row of the designs table below carries the source for its own attribution.

Family lines

3 of 4 connected1 Heritage line2 under other senses

4 designs are attributed to Seiko Instruments Inc. (SII). 3 of them sit in 1 recorded family line under the Heritage sense of the word — it is drawn below. The other 1 stands alone in this sense, and no other sense of “family” puts it in one either: this corpus records no relative for it — not that none exists.

accepteddisputed
Line 1Seiko 4R36 / NH36 — Heritage family: 3 calibers, 2 sourced lineage links. 3 of them are attributed to Seiko Instruments Inc. (SII).Drag to explore.
100%drag to pan · hover a caliber to isolate its line · scroll the page normallyopen the full family view →
derived fromderived fromSeiko 4R36 / NH36 — open caliber pageSeiko 4R36 / NH362011Seiko Instruments Inc. (SII)1 exec · grade ?Seiko 6R15 — open caliber pageSeiko 6R152006Seiko Instruments Inc. (SII)1 exec · grade ?Seiko 7S26 — open caliber pageSeiko 7S261996Seiko Instruments Inc. (SII)1 exec · grade ?
Other senses of “family”2 lines

A cluster profile is a rule for what counts as descent, not an opinion about it. These are the lines this maker’s designs sit in under the site’s other rules — a broader one keeps edge types that the Heritage sense does not traverse, so the same root can appear here with more members. Nothing below is a relationship the corpus does not hold; it is the same claims read under a different filter, and each view says on its own page which edge types it traversed.

LineSenseCalibersThis maker’s
Seiko 4R36 / NH36Everything (debug)33
Seiko 4R36 / NH36Based-on star (WatchBase sense)33

Corporate history

These edges move ownership and names, never designs. This is why “who made the 7750 in 1978” and “who makes it now” are different questions with different answers about the same construction.

FromRelationToPeriodStatusClaim
Seiko Instruments Inc. (SII)subsidiary ofseiko-group2009-10-01–presentacceptedcd8ad0788d3cb1b79

The export gives these edges a claim id but no inline reference, so the claim id is shown as the citation anchor rather than a source link.

Designs attributed to Seiko Instruments Inc. (SII)

DesignationRoleAttributedIntroducedFamilySources
Seiko 4R36 / NH36producerno dates given20113 calibers
Seiko 6R15producerno dates given20063 calibers
Seiko 7S26producerno dates given19963 calibers
Seiko NH35 / 4R35producerno dates given2011stands alone

Sources

  1. 1
    watchuseek.com
    https://www.watchuseek.com/threads/seiko-4r36-vs-7s26-major-improvement-or-just-added-hack-hand-wind.937856/
    forumtier 4retrieved 2026-08-241 fact on this page
  2. 2
    Caliber Corner
    https://calibercorner.com/seiko-caliber-6r15/
    curated dbtier 2retrieved 2026-08-242 facts on this pagecited, never crawled
  3. 3
    Caliber Corner
    https://calibercorner.com/seiko-caliber-nh36/
    curated dbtier 2retrieved 2026-08-241 fact on this pagecited, never crawled
  4. 4
    namokimods.com
    https://www.namokimods.com/blogs/namokitimes/can-you-build-seiko-mods-with-the-7s26-4r36-or-6r15-calibres-6
    presstier 3retrieved 2026-08-241 fact on this page
  5. 5
    Seiko Time Module Inc.
    https://www.timemodule.com/en/
    manufacturertier 1retrieved 2026-08-241 fact on this page
  6. 6
    Caliber Corner
    https://calibercorner.com/seiko-caliber-nh35/
    curated dbtier 2retrieved 2026-08-241 fact on this pagecited, never crawled